The pharmaceutical art has long recognized the utility of gelatin as a "shell" material for the encapsulation of medicaments into a convenient dosage form. Gelatin is easily processed and may be colored with various pharmaceutically acceptable colorants. Gelatin is generally divided into Type A for acid extracted gelatin and Type B for base extracted gelatin. Combinations of gelatin are useful in this art. As used in the pharmaceutical art gelatin is prepared in a mixture with water and glycerin or other plasticizer to the desired flexibility. The amount of water and glycerin is frequently varied with a view to the desired final hardness of the shell. Commonly those skilled in the art use hard (0.4:1 glycerin to gelatin) for oral, oil-based, or shell softening products and those destined for hot humid climates, medium (0.6:1) for oral, tube, vaginal oil-based, water-miscible or shell-hardening products and those destined for temperate climates, and soft (0.8:1) for tube, vaginal, water-miscible based or shell-hardening products and those destined for cold dry areas. A draw back to the use of gelatin is its propensity deteriorate by drying out and cracking or becoming brittle.
Ethanol and other alcohols are well known pharmaceutical diluents, excipients and solvents used in compounding numerous dosage forms. Alcohol is also a drying agent and thus limited in its use with gelatin. It is generally understood that a gelatin preparation such as a gelatin capsule must be less than about 5% ethanol lest the ethanol dry the gelatin and cause unacceptable deterioration of the gelatin.
The Theory and Practice of Industrial Pharmacy, 3rd Ed., p402, Leon Lachman et al.; Lea & Febiger, Philadelphia (1986) states that water-miscible liquids which are also volatile cannot be major gelatin capsule constituents. Alcohol is specifically cited as such a constituent and about 5% of encapsulated material is stated to be the maximum amount.
Thus a very useful article would be a gelatin pharmaceutical dosage form that can encapsulate medicaments with over 5% ethanol and not deteriorate.